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Study Finds Adolescent Diet Influences Sex Hormone Levels

PHILADELPHIA (January 9, 2003) — A new study shows that girls who eat a higher fat diet during puberty may increase the levels of sex hormones in their blood that have been related to breast cancer in adults. The study sponsored by the National Cancer Institute and the National Heart, Lung, and Blood Institute at the National Institutes of Health, is published in the January 15, 2002, issue of the Journal of the National Cancer Institute.

"Our study shows that even a modest reduction in the consumption of fat during puberty resulted in lower levels of sex hormones such as estrogen and progesterone," explained Joanne F. Dorgan, MPH, PhD, a member of the population science division at Fox Chase Cancer Center and lead author on the study.

Diet during adolescence has been hypothesized to influence risk of breast cancer in adults. Diet influences sexual maturation and growth during adolescence, and women who mature earlier and are taller are at an increased risk of developing breast cancer. Although case-control studies generally do not support an association of childhood diet with breast cancer, their reliance on the adult's recall of diet in the distant past may misclassify some individuals, biasing results.

"Although we do not know if lower hormone levels during adolescence will influence breast cancer risk in adulthood, adolescence is a time of rapid growth and maturation of the breasts," Dorgan explained. "Estrogens and progesterone contribute to the regulation of this process. Lower levels of these hormones during adolescence could potentially protect against breast cancer by altering breast morphology or by decreasing the rate of cell turnover and proliferation, which would decrease the occurrence of chance mutations. Lowering estrogen levels also may decrease the exposure of the breast to some estrogen metabolites that are believed to be cause cancer."

This study, completed in 1997, evaluated the effect of a lower-fat diet on serum hormones of 286 healthy girls beginning at 8 and 10 years of age. The girls were randomly assigned to two separate groups. One group had no dietary intervention. The second group received an intervention that promoted consumption of less total fat, saturated fat, and cholesterol. Most girls were in the study for at least seven years.

After five years, the girls who received diet intervention had a 30 percent lower level of estradiol (the most potent, naturally occurring estrogen) in their blood during the follicular phase of their menstrual cycles (first half of cycle before ovulation) compared to the girls who did not receive diet intervention. After seven years, girls in the intervention group had 50 percent lower progesterone levels during the luteal phase of their cycles (second half of cycle after ovulation).

"So often, we hear of people changing their diets late in life to prevent cancer and other chronic diseases," says Dorgan. "While that is a good idea, this study supports the importance of having a good diet that begins during childhood and adolescence."

The study was conducted as an ancillary study to the Dietary Intervention Study in Children (DISC), a multi-center randomized controlled clinical trial to test the safety and efficacy of a cholesterol-lowering dietary intervention in children. It was conducted in the Division of Cancer Prevention and Control and the Division of Cancer Epidemiology and Genetics at the National Cancer Institute in collaboration with the Division of Epidemiology and Clinical Applications, National Heart, Lung, and Blood Institute, the six DISC clinical centers and coordinating center.

Fox Chase Cancer Center, part of the Temple University Health System, is one of the leading cancer research and treatment centers in the United States. Founded in 1904 in Philadelphia as one of the nation’s first cancer hospitals, Fox Chase was also among the first institutions to be designated a National Cancer Institute Comprehensive Cancer Center in 1974. Fox Chase researchers have won the highest awards in their fields, including two Nobel Prizes. Fox Chase physicians are also routinely recognized in national rankings, and the Center’s nursing program has received the Magnet recognition for excellence four consecutive times. Today, Fox Chase conducts a broad array of nationally competitive basic, translational, and clinical research, with special programs in cancer prevention, detection, survivorship, and community outreach. For more information, call 1-888-FOX CHASE or (1-888-369-2427).

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